Weathering and Erosion — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
Weathering is the movement of rock pieces from one place to another by wind or water.
Corrected: Weathering is the breaking down of rocks into smaller pieces by natural forces like water, ice, or wind.
The corrected sentence is: "Weathering is the breaking down of rocks into smaller pieces by natural forces like water, ice, or wind.". The original sentence "Weathering is the movement of rock pieces from one place to another by wind or water." contained an error that needed to be fixed.
2. Fix the sentence:
Erosion only happens in deserts because wind is the only force that moves sediment.
Corrected: Erosion happens everywhere because water, wind, ice, and gravity can all move sediment.
The corrected sentence is: "Erosion happens everywhere because water, wind, ice, and gravity can all move sediment.". The original sentence "Erosion only happens in deserts because wind is the only force that moves sediment." contained an error that needed to be fixed.
3. Fix the sentence:
Chemical weathering breaks rocks apart by freezing water expanding in cracks.
Corrected: Physical weathering breaks rocks apart by freezing water expanding in cracks; chemical weathering changes the minerals inside rocks.
The corrected sentence is: "Physical weathering breaks rocks apart by freezing water expanding in cracks; chemical weathering changes the minerals inside rocks.". The original sentence "Chemical weathering breaks rocks apart by freezing water expanding in cracks." contained an error that needed to be fixed.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. The breaking down of rocks into smaller pieces is called weathering.
Weathering is the process that breaks rocks into smaller pieces through physical or chemical means.
2. Water, wind, and ice can carry rock pieces away in a process called erosion.
Erosion is the movement and transport of weathered rock and soil by water, wind, ice, or gravity.
3. When eroded sediment is dropped in a new location, it is called deposition.
Deposition occurs when the agent of erosion (water, wind, glacier) slows down and drops the sediment it was carrying.
4. Water freezing in rock cracks causes physical weathering.
Frost wedging (ice breaking rock) is physical weathering because it changes the size and shape of rock without changing its chemical composition.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Name two natural forces that cause erosion and explain how each one moves sediment.
Sample answer: Water carries loose soil and rock downhill in streams and rivers. Wind picks up small sand particles and blows them to new locations.
Water: kinetic energy moves particles; wind: same principle with air as the medium. Both deposit sediment when they slow down.
2. How does a pothole in a road form through weathering?
Sample answer: Water seeps into small cracks in the road. When the water freezes it expands and makes the cracks bigger. Over time the surface breaks apart and a pothole forms.
Freeze-thaw weathering: water (liquid) → ice (expands 9%) → repeated cycles → crack widens → pothole forms.